1. Field of the Invention
The present invention relates to methods for detecting gas, and more specifically, it relates to absorption spectroscopy as a mechanism for gas detection.
2. Description of Related Art
Gas analysis is conventionally performed using laboratory analytical techniques, e.g., gas chromatography or mass spectrometry (GC-MS), which do not satisfy current device and material constraints for unattended, flexible ground sensors, or for lightweight, highly sensitive systems for avionic operations. Absorption spectroscopy is a powerful alternative approach for gas in-field detection and identification, and several interesting techniques have been developed including tunable diode laser absorption spectroscopy (TDLAS). Typically, this occurs in the infrared (IR) region of the spectrum. Recently, micromechanically tunable vertical-cavity surface-emitting lasers (VCSELs) have been implemented in such fashion for near infrared (NIR) spectroscopy. Unfortunately, many existing TDLAS systems exhibit drawbacks that limit their deployment, including the need for cryogenic cooling, a requirement for a bulky multipass cell, or a long hollow or porous fiber with a relatively slow time response.